Bump System.Drawing.Common from 6.0.0 to 8.0.6 in /src.csharp

Bumps [System.Drawing.Common](https://github.com/dotnet/winforms) from 6.0.0 to 8.0.6.
- [Release notes](https://github.com/dotnet/winforms/releases)
- [Changelog](https://github.com/dotnet/winforms/blob/main/docs/release-activity.md)
- [Commits](https://github.com/dotnet/winforms/commits/v8.0.6)

---
updated-dependencies:
- dependency-name: System.Drawing.Common
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

src.csharp/AlphaTab/AlphaTab.csproj

@@ -27,6 +27,6 @@
       <PackageReference Include="Microsoft.CSharp" Version="4.7.0" />
       <PackageReference Include="SkiaSharp" Version="2.88.8" />
       <PackageReference Include="SkiaSharp.HarfBuzz" Version="2.88.8" />
-      <PackageReference Include="System.Drawing.Common" Version="6.0.0" />
+      <PackageReference Include="System.Drawing.Common" Version="8.0.6" />
     </ItemGroup>
 </Project>